From The Author: An end center marking jig is a simple and very useful jig to have in the shop. It is used to locate and mark the center at one or both ends of your square or round stock. great for locating and marking the center of dowels, etc. This shop jig uses very little scrap wood and takes no time to build.

In the video I explain a little about 30-60-90 and 45-45-90 triangles as they are used in the shop along with how the 30-60-90 triangle is used in the jig as the marking guide. – Website